Basic liberty, according to Rawls's first principle of justice, is not to be sacrificed for other values such as wealth. And, according to his second principle of justice, the material well-being of the worst-off members of society is not to be sacrificed to benefit better-off members of society. These trade-offs would be unjust, according to Rawls, no matter how small the sacrifice or how large the offsetting benefit. A decision-maker conforming to Rawls's theory, who is unwilling to sacrifice some values in favor of others, has lexical preferences. Lexical preferences, however, are not encountered in studies of consumer demand for market goods. Since goods trade off within the range of choices studied in demand theory, it seems to economists that political values ought to trade off as well.